Per the instructions for Form D-40 Individual Income Tax:

District Code section 47-1803.03 (c) states, “Every individual who claims the standard deduction on his or her federal income tax return shall claim the applicable standard deduction specified in section 47-1801.4(26). Every individual who itemizes the deductions on his or her federal income tax return shall itemize the deductions permissible under this chapter. If a husband and wife file separate returns, the applicable standard deduction shall not be allowed to either spouse or domestic partner if the net income of one of the spouses/domestic partners is determined by itemizing deductions.” Each spouse/domestic partner can claim only their own itemized deductions.

TaxACT calculates your DC return based on the federal deductions being taken.